1. Field of the Invention
The present invention relates generally to magnetized tools of various types, and more specifically to an elongate tool having a selectively extendible and retractable magnetic tip. The present magnetic tool is particularly well adapted for use as a valve lifter or tappet raising tool for use in removing the camshaft from the block of an engine, but may be modified or adapted for other purposes as well.
2. Description of the Related Art
Many, if not most, U.S. automotive and truck engines are constructed with the valve actuating camshaft located in a bore within the engine block, offset from the engine crankshaft. These engines universally use the overhead valve principle, with the valves being actuated by pushrods extending upwardly from the camshaft lobes and acting on rocker arms atop the cylinder head to actuate the valves. Such engines nearly universally use hydraulic tappets or lifters riding on the cam lobes to actuate the valve pushrods. Hydraulic lifters provide many advantages over solid lifters, particularly providing quieter valve train operation and greatly reducing the need for periodic valve adjustments.
From time to time it may be necessary to remove the camshaft from such an engine, due to wear of the cam lobes, desire to install a higher performance cam, or for some other reason. In the past, the labor required for such a job was relatively high, primarily due to the need to remove the cylinder head(s) in order to access the lifters or tappets before removing the camshaft. If the lifters are not removed prior to attempting to remove the cam from its bore in the engine block, the lifters drop downwardly past the cam lobes and bearings as the withdrawal of the camshaft from the block is initiated. As the camshaft continues to be withdrawn, the succeeding cam lobe or bearing encounters the dropped lifter from the adjacent valve in the adjacent cylinder, which blocks further withdrawal of the camshaft from the block. The conventional procedure in providing sufficient clearance to remove the cam from the block is to spend the additional time and labor to remove the cylinder head(s) from the engine to gain access to the lifter bores, and then remove the lifters from their bores.
The present invention provides a solution to the above problem in the form of a magnetic tool which is particularly well adapted for the lifting of hydraulic valve lifters or tappets from the bottoms of their bores in a camshaft-in-block, overhead valve (OHV) gasoline or diesel engine. The present invention comprises a series of embodiments of relatively thin, elongate tools having selectively extendible and retractable magnets in their working tips. Various mechanisms are provided for extending and retracting the magnet in the tip of the tool, as desired. The present tool is used by merely loosening the rocker arms atop the cylinder head of the engine and shifting the rocker arms to one side to access the valve pushrods. The pushrods are withdrawn from their passages through the cylinder head(s), and one of the present tools is inserted into each of the pushrod passages through the head and into the block to contact the valve lifter at the bottom of the passage. The tool is then lifted slightly, withdrawing the lifter from its normal position against the face of the cam lobe to allow withdrawal of the cam from the block. A collar is preferably provided along the shank of the tool to rest against the head and hold the magnetic end of the tool at a sufficient height to maintain the lifter clear of the cam lobes. One of the present tools is applied in each pushrod passage to hold all of the lifters or tappets simultaneously during camshaft removal and installation. The present tool may be modified slightly to provide other functions as well, by forming a square, hexagonal, or other shaped receptacle at the working end to grip a square drive socket, an interchangeable tool bit, or other component as desired.
A discussion of the related art of which the present inventor is aware, and its differences and distinctions from the present invention, is provided below.
U.S. Pat. No. 4,575,143 issued on Mar. 11, 1986 to Irving J. Nast, titled “Pick-Up Tool,” describes a mechanical type grasping tool having a series of outwardly springing fingers extending from the tubular end thereof. The fingers are normally withdrawn into the end of the tube by an axial spring at the opposite end of the device. The Nast tool differs from conventional finger-type tools by having a toroidally shaped magnet installed at the finger end of the tool. This configuration teaches away from the present invention, in which the magnet is retractably located within the end of the tube, rather than having mechanical fingers within the tube and the magnet fixed about the exterior of the end of the tube, as in the Nast device. Moreover, Nast does not note any dimensions for the diameter of the magnet at the gripping end of his tool. It would appear that the diameter of the magnet is too large to pass through the relatively narrow pushrod bore provided through the head of a conventional OHV engine.
U.S. Pat. No. 5,169,193 issued on Dec. 8, 1992 to John J. Stelmach, titled “Magnetic Pickup Tool,” describes an elongate tool having a retractable magnet in the working end or tip thereof. A flexible wire extends through the tubular shank of the tool to control the position of the magnet. As in the case of the Nast tool above, the Stelmach tool is quite flexible in order to provide the versatility required for picking up various objects which have fallen into relatively inaccessible locations. Stelmach provides a rigid tubular jacket around his flexible tube, but the rigid tube is removable. In contrast, the present tool includes a rigid tubular housing as a permanent component of the device. As in the Nast tool discussed immediately above, Stelmach does not make any disclosure regarding the diameter of his tool and its suitability for passage through the relatively narrow bore provided in a cylinder head for a valve pushrod. Moreover, neither Stelmach nor Nast provides any means of securing their tools in position at a predetermined height within a passage, as provided by the present tool.
U.S. Pat. No. 5,265,887 issued on Nov. 30, 1993 to John J. Stelmach, titled “Magnetic Pickup Tool,” is a continuation in part of the '193 U.S. patent to the same inventor, discussed immediately above. The '887 continuation patent includes a different, more rounded tip at the working end of the tool, but the same points of distinction between the '193 tool and the present invention are seen to apply here as well.
U.S. Pat. No. 5,472,253 issued on Dec. 5, 1995 to John R. Resor, titled “Welder's Debris Pick Up Tool” describes a rigid, elongate tool having a fixed magnetic shank extending from a non-magnetic handle to the working tip of the device. This enables the device to pick up magnetically attractive pieces at any point along its length. The provision of an exposed magnetic shaft is undesirable in the present invention, as it would make the tool difficult to position within a cast iron engine block.
U.S. Pat. No. 5,647,623 issued on Jul. 15, 1997 to Hsuan-Sen Shiao, titled “Telescopic Shaft Magnetic Retriever,” describes a device having a multiple segment telescoping shaft with a small battery powered light coaxially installed at the working tip thereof. A single button type magnet is placed over the end of the light. The magnet is not retractable, and the diameter of the device would appear to be too large to fit within the narrow pushrod bore through the cylinder head of an engine, due to the light assembly at the working end thereof.
U.S. Pat. No. 5,799,999 issued on Sep. 1, 1998 to Cyril B. Schneider et al., titled “Magnetic Retrieving Tool,” describes another flexible elongate tool having a retractable magnetic tip. The magnetic tip may be locked in an extended or retracted configuration, as desired. The flexibility of the device results in a tool more closely resembling the tool of the '143 U.S. patent to Nast, than it does the present invention.
U.S. Pat. No. 5,810,409 issued on Sep. 22, 1998 to Richard J. Hardie, titled “Magnetic Retrieval Device,” describes another device having a flexible shaft (formed of rubber hose, in this case) with a magnet in the working tip thereof. While the magnet is retained by a wire extending the length of the tube to a handle at the handgrip end of the device in at least one embodiment, Hardie makes no provision for the retraction or extension of the magnet beyond the tip of the tube. Moreover, Hardie specifies that the tube has a ¼ inch internal diameter, which in view of the cross sectional drawings provided would appear to result in a tool having an external diameter too large to pass through the pushrod bore in the cylinder head of an engine.
U.S. Pat. No. 5,945,901 issued on Aug. 31, 1999 to Edward S. Coleman, Jr. et al., titled “Magnetic Head For Magnetic Pick-Up Tool,” describes various embodiments of an elongate tool having a magnetic working tip. A slidable, magnetically attractive sleeve is provided over the magnet to concentrate the magnetic attraction of the magnet. FIG. 6 of the drawings shows a hand grip having finger indentations therein, with the hand grip having about the same diameter as the sleeve disposed about the magnet. The magnet with its surrounding sleeve is thus apparently too large to fit into a pushrod bore through the cylinder head of an engine, which operation is one of the primary purposes of the present invention.
U.S. Pat. No. 6,048,073 issued on Apr. 11, 2000 to Hsuan-Sen Shiao, titled “Telescopic Hand Tool,” describes an elongate tool having a series of interchangeable tool elements for the working end thereof. The working end of the tool includes a magnet within a socket, with the socket having external threads thereon. Most of the tool elements secure to the working end of the tool shank by means of an external socket having internal threads which secure to the socket of the working end of the tool shank. The device includes provision for screwdriver bits and the like which insert into the socket of the working end of the tool, in at least some embodiments. However, the magnet is fixed in a permanently retracted configuration in order to provide a magnetically retractable receptacle for the tool bit, as is known in the art. This configuration cannot be used to lift a magnetically attractive component which is larger than the internal diameter of the receptacle, as the magnet is positioned at some distance from the article to be attracted and cannot exert sufficient magnetic force to draw the article away from its initial position. In contrast, the present magnetic tool provides for the selective extension of the magnet beyond the working end socket of the tool, to allow the magnet to come into direct contact with the object being magnetically moved.
U.S. Pat. No. 6,065,787 issued on May 23, 2000 to Robert M. Jarosch, titled “Retriever Tool,” describes a tool having double opposed telescoping end sections from a central portion. Several means of attracting or attaching one of the working ends of the tool to another component are provided, including a magnet disposed in one end of the tool. The magnet cannot be retracted within its installed end, as provided by the present invention. Moreover, the increasingly larger widths or diameters of the telescoping sections toward the working ends of the tool, preclude insertion of either working end into the relatively narrow pushrod passage in the cylinder head of an engine.
U.S. Pat. No. 6,315,340 issued on Nov. 13, 2001 to Andrew Chen, titled “Multifunctional Pick-Up Tool,” describes a device having a retractable mechanical claw or fingers selectively extending from the working end, with a small light and a small magnet installed beside the opening for the claw. The plurality of components in the working end of the tool results in the working end being too large to fit within the pushrod passage of an engine cylinder head, as provided by the present invention.
U.S. Pat. No. 6,325,433 issued on Dec. 4, 2001 to Roy V. Nicholson et al., titled “Magnetic Metal Object Retriever With Cover,” describes a hand carried tool having a relatively large diameter, flat magnetic plate extending from one end. The tool is drawn over a surface (floor, etc.) by a walking person carrying the device and used to pick up magnetically attractive debris (nails, screws, etc.). A magnetically permeable cover is removably installed over the magnet, with the magnet attracting articles through the cover. The cover is removed to remove the attracted articles from the tool, with the articles falling from the cover when it is removed. The magnet is much too large to be inserted within a pushrod bore of an engine cylinder head, and no retraction of the magnet is provided by Nicholson et al.
U.S. Patent Publication No. 2003/173,788 published on Sep. 18, 2003 and applied for by James Fussell et al., titled “Recovery Device And Unit,” describes a hand carried device having a retractable head which carries an adhesive pad thereon. The pad is used to pick up various articles which may be hazardous in the event of direct contact to a person. When the adhesive pad has been used it is retracted into the head, which dislodges the pad from its attachment to the tool for disposal. Fussell et al. make mention of an alternative magnetic means, but no magnetic embodiment is specifically disclosed. In any event, the Fussell et al. tool is much too large for use in the intended environment of the present invention.
U.S. Pat. No. 6,705,654 issued on Mar. 16, 2004 to L. Johnny Slauf, titled “Frisbee Golf Disc Retriever And More,” describes another relatively large, hand carried tool having a folding tubular body secured by an elastic tension member extending therethrough. This construction cannot provide for a rigid compression member extending through the body to selectively extend a magnet from the working end thereof, as provided by the present invention. As in the case of Fussell et al., Slauf makes mention of a magnetic component on the working end of his device, but none of the pickup devices disclosed by Slauf can be retracted into the working end of the tool.
U.S. Design Pat. No. 378,337 issued on Mar. 11, 1997 to Mark F. Reynolds et al., titled “Telescoping Magnet,” illustrates a design having a swivel attached magnet at the working end thereof, with a series of relatively short telescoping sections extending from the handle portion of the device. No retraction of the magnet into the working end of the device is apparent.
U.S. Design Pat. No. 446,701 issued on Aug. 21, 2001 to Edward S. Coleman, Jr. et al., titled “Magnet Head for Magnetic Retrieval Tool,” illustrates a design for a magnetic tool head, apparently for use with the tool of the '901 U.S. patent to the same inventors. The device of the '901 U.S. patent was discussed further above, with the same points noted in that discussion appearing to apply here as well. In addition, it is noted that no retraction of the magnet is apparent in the device of the '701 U.S. Design Pat.
British Patent No. 584,156, published on Jan. 8, 1947, titled “An Improved Permanent Magnet Appliance,” describes a tool having a flexible shaft with a bar magnet at one end and a horseshoe magnet at the opposite end. No means of retracting the magnet into a sleeve at either end, is disclosed.
British Patent No. 639,039, published on Jun. 21, 1950, titled “Improvements In Or Relating To Permanent Magnets,” describes a tool comprising an elongate rod of flexible metal with a generally cylindrical housing for a magnet attached to the working end of the rod. The magnet is permanently affixed in the end of the tool, and cannot be retracted or extended. One embodiment discloses the magnet being housed in the base of a socket with the socket walls extending beyond the magnet, as in conventional screwdrivers and the like having interchangeable bits. The socket is adapted to f it the head of a bolt or the like, which would apparently make the outer diameter of the socket too large to fit into a pushrod passage in the cylinder head of an engine. The patent describes various uses for the tool, including withdrawing parts or debris from engine oil sumps, transmissions, and differentials, but these areas are universally provided with relatively large access panels or are removed for mechanical work. Thus, the interiors of such components are readily accessible with large tools.
Finally, German Patent No. 929,300 published on Jun. 23, 1955, includes only a single drawing apparently illustrating a tool having a selectively retractable magnet within the working end. A spring within the device apparently urges the magnet to an extended position, with a finger grip provided to retract the magnet within its housing at the working end of the tool. A cover is placed over the end of the magnet and housing, thereby completely enclosing the magnet. It would appear that withdrawal of the magnet from the cover would dislodge any magnetically attracted material from the working end of the tool. Thus, the device of the '300 German Patent appears to be more closely related to the magnet and removable cover of the '433 U.S. patent to Nicholson et al., discussed further above, than it is to the present invention. In any event, the relatively wide flare of the working end of the device of the German disclosure would appear to preclude its use in retracting valve lifters or tappets, for which purpose the present invention is adapted.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus a magnetic tool solving the aforementioned problems is desired.